This invention relates generally to a mine roof truss and in particular to a transition plate for a mine roof truss. The transition plate joins the inclined and horizontal chords of the mine roof truss.
Mine roof trusses, as shown in U.S. Pat. Nos. 3,509,726 to White (1970): 3,505,824 to White (1970); 3,427,811 to White (1969); 2,667,037 to Thomas et al (1954); and 1,559,560 to Doughty (1925), have been designed to support mine roofs. The trusses include generally two inclined chords and a horizontal chord. The inclined chords are usually mine roof bolts which extend into holes in the mine roof at about a 45.degree. angle. The mine roof bolts are anchored in the holes by well known means such as expansion shells or resin bonding. The horizontal chord or tie member may be made from rods or wire rope.
A critical member of a mine roof truss is the transition plate which ties together the inclined chord members and the horizontal chord member. The transition plate must have sufficient rigidity and strength to withstand the high horizontal and inclined forces. In addition, the transition plate should have a low profile, i.e. extend downwardly from the mine roof a minimum distance so as to allow the maximum working space between the mine floor and the roof. Furthermore, the transition plate should be designed to allow the inclined and horizontal chords to be readily installed and tensioned and be so arranged as to allow the load in the chords to be readily measured. It is also important that the transition plate be relatively light in weight so as to facilitate handling and installation. Finally, the transition plate should be economical to manufacture.